The Only Pruning Rule You Need to Know: The Three Ds Explained

Pruning can be a daunting task. If you’ve ever found yourself wondering, ‘What if I cut too much off?’ or “Will I kill the plant?’, you’re certainly not alone. And the bigger the plant, the scarier it is. But there’s a very simple rule that will guide your winter pruning. Follow the Three Ds rule and you really can’t go wrong.

The ‘Three Ds’ stand for Dead, Diseased and Damaged wood, and they’re the cornerstones of winter pruning. While summer pruning aims to control growth and refine shape, pruning in winter is all about improving the plant’s health and structure. It’s done between late November and March, depending on your USDA zone, when deciduous trees and shrubs are dormant. Pruning plants while they’re still deep in their winter slumber causes less stress and, because sap isn’t flowing strongly, the cut stem ends heal quickly.

Winter pruning also sets your plants up for strong, healthy growth through spring and summer, and the lack of leaves makes it easy for you to see what you’re doing.

1. Dead

Start by removing any stems, branches or twigs that are dead. Lifeless wood serves no purpose, and creates an easy entry point for disease, so be ruthless! It’s best to cut off dead matter flush with the stem or branch it’s growing from or, if it’s just a small section, just above a healthy bud.

Not sure if a stem is dead or just asleep? Dead wood is typically brittle, lacks color and, if you try the scratch test with a fingernail or hand-pruner blade, doesn’t show the thin green layer of cadmium just under the bark.

2. Diseased

Next, look for signs of disease such as cankers, fungal growths, distorted wood or discoloured areas. You might also spot signs of infection like galls (swollen growths), leaking sap or lesions. These are likely to spread once the plant wakes from its winter slumber, so it’s important to remove any affected sections.

Err on the safe side and cut well below the diseased area – as much as a foot into healthy wood on an established tree. It’s also vital that you sterilize your hand pruners or saw after each and every cut to ensure you don’t pass the infection to healthy parts of the plant. It’s easy to do: fill a jar or bucket with a 1:10 ratio bleach and water and thoroughly dunk your tools between cuts.

You can help to prevent future disease, too. Congested areas, where there’s insufficient room for ample airflow, create the perfect conditions for fungal disease, so it's a smart move to thin stems here.

3. Damaged

After winter storms and snowfall, trees and shrubs often have damaged branches and stems with ragged edges or deep cracks which could easily become infected. Look for scars on the bark, too, where two branches are rubbing against each other. Remove all damaged stems, cutting back to a just above a healthy bud, the branch it’s growing from, or the main trunk. In the case of rubbing branches, remove the weaker one.

Look for stems that are likely to become damaged as well. If summer growth will lead to lead to a stem rubbing against another, or a branch reaching a wall or fence, you may as well avoid the problem and snip it off now.

4. Direct Energy

Hold on, there are only supposed to be three Ds, right? There’s one last D we reckon should be added to the rule. While you’re removing the dead, diseased and damaged sections of the plant, keep in mind that all your cuts direct energy into healthy new growth.

The fresh stems will grow in the same direction as the bud below the cut you make, so by choosing which bud you cut to, you can easily direct the plant’s energy in whichever direction you like. For example, if you want to reduce congestion or widen the growth, simply prune to just above an outward-facing bud. Remembering this rule also means you can avoid cuts that might lead to potential damage, such as rubbing stems.

By removing weak stems, you can direct the plant’s precious energy into its stronger stems, as well.

To ensure the plant doesn’t waste its energy on healing, either cut stems flush to those they’re growing from, or a quarter-inch above a bud, ensuring there are at least three buds on the stem (this is simply a safety policy: one or two buds may fail, but it’s very unlikely that three will). Angle your cuts away from the buds, so water runs off quickly.

Pruning Essentials

Most deciduous trees, summer-flowering shrubs, and winter-flowering shrubs (once they’re done blooming) can be pruned now, so what are you waiting for? Happy pruning!